Insulated electrical conductors



80 p a cotton base for support, carbonization of the Patented Nov. -3, 1936' UNITED STATES PATENT OFFICE- INSULATED, ELECTRICAL CONDUCTOBS Samuel Ruben. New York, N. Y., aslignor to Vega Manufacturing Corporation, Wilmington, Del.,- a corporation of Delaware No Drawing. Application January 14.1930.

- Serial No. 420.818

' serum. (01. 173-264) This invention relates to an improved type of insulated electrical conductor and to a method of making the same. 4

One of the objects of the invention is to produce an insulated wire or conductor capable of withstanding high temperatures without melting, decomposing and without destruction of insulation resistance of the insulation.

Other objects of the invention will be apparent as the description thereof proceeds.

In my priorPatent No. 1,908,792 dated May 16th, 1933, I describe an. insulation resistance which commercially has been proved to withstand temperatures as high as 1200 0. without electrical leakage or mechanical breakage. In the patent above mentioned, the coating is used to form an integral refractory unit with an element such as tungsten.

In this invention, the coating described in Patent No. 1,908,792 finds its chief use when applied to good conductors such as copper and has been found to eliminate many of the difficulties experienced with insulated wires of the prior art;

In the prior art, there have been used organic forms of insulation coating such as rubber, which tend to carbonlze and lose their insulation resistance, especially if operated at high temperatures or they tend to oxidize by virtue of high tension production of ozone. In the case of fire proof coating such as asbestos used in combination with base occurs.

In the wire of my invention, in a preferred form, the coating is of the inorganic type and comprises forming a layer integral with the conductor base, of aluminum oxide by means of aluminum chloride as the suspension and reacting material.

Where high temperatures are encountered, I have found that the most important factor in the coating is to have no binder or residual inactive -(AlCl3) in water as a suspension material readily adheres as a coating and when baked and sintered forms a tough, dense, hard and smooth layer that'does not chip or-flake. Due to the integral structure obtained, suflicient flexibility is obtained for bending around forms or winding on spools.

In preparing the mixture, the crystallized aluminum oxide is finely ground'and added to a 5 25% solution of aluminum chloride. The coating is preferably applied by machine methods in the following manner:

The wire (copper preferably) is chemically cleaned and is passed over a rotating pulley which 10- rotates in a cup containing the insulation mixture. In passing over the pulley, the wire is uniformly coated with a thin layer of the insulation. The coating is then passed through a furnace which. is maintained at about 700 C. On entering the 15 heater, the coating is. dried and the higher tem-' perature decomposes the aluminum chloride and eliminates hydrogen chloride by its substitution for oxygen. The important factor is involved in the oxychloride reaction This treatment andreaction is repeated three times, after which the wire is spooled one. large diameter spool. The thickness of the finished coating is about 5 mils. The heating furnaces and coating pulley are mounted in a straight line so that when the untreated and cleaned wire is passed over the three coating cups and through the furnaces it is in finished state and ready to wind on the large spool.

When the reactions are completed, it will be found that the wire has been coated with a very desirable insulation resistance "material. The insulation resistance depends upon the thickness of coating and the size of the aluminum oxide crystals.

The first or relatively low temperature hardening is probably due to the formation of an oxychloride and melting of the aluminum chloride 40 crystals (2A1Cl36Ha). Another cementation agent is probably the cupric chloride formed at the surface of the copper wire, for it is noted that the wire becomes etched due to a reaction that occurs at its surface when heated in contact with the coating.

If the coating is applied to a wire that will withstand 1000 C. without melting, for example, where the coated wire is used to wind resistances with nickel or nichrome wire, it is heated to a 5 but aluminum fluoride or bromidecan also be used. Other insulating oxides such, as .beryl, beryllium oxide, can be used with aluminum chloaluminum in hydrochloric, acid or by dissolving gelatinous aluminum hydroxide in hydrochloric acid.

7 Aluminum chloride has been found the mostpractical of the halogen compounds of aluminum;

ride as the halogen compound.

almost infinitesimal sin, builds up, a material within the intercrystalline space of the solid. oxide this condition giving strength and. insulat- 1 ing resistance otherwise not obtainable. Where excessively high temperatures are not encountered a small percentage of a binding or v ing of aluminum oxide derived from a mixture of ground aluminu'm'oxide and a halogen compound of aluminum applied to the conductor and heated to the decomposition point of the halogen com- 1 if, po md In general, the fundamental requirement for the suspension material of thisinvention is to; use a salt capable of disassociating and displacing its halogen component for oxygen so asto" leave only an active material which, due to the 2; A non-refractory conductor having a-coating of-aluminum oxide derived from a mixture of ground aluminum oxide and aluminum chloride applied to the conductor andheated to the decomposition point of the chloride.

3. A copper wire having a coatingof aluminum oxide derived from a mixture of ground alumi-- num oxide and a halogen compound of aluminum applied to the conductor and heated to the decomposition point of the halogen compound.

, SAMUEL RUBEN. 

